This research career award is a plan to foster the development of Dr. Daniel Bonthius into an independent neuroscientist. Dr. Bonthius is a pediatric neurologist with a special interest in the adverse effects of environmental agents, including congenital viral infections, on fetal brain development. His long term career goal is to become a physician scientist capable of making meaningful contributions in neuroteratology. The research techniques on which Dr. Bonthius will focus are those of molecular neurobiology, which are of key importance in the field of neuroteratology. Dr. Bonthius will acquire his new research skills through a combination of didactic courses, skills workshops, technical seminars, and through his research into the neuroteratology of lymphocytic choriomeningitis virus (LCMV) infection. LCMV is a prevalant virus which can serverely damage the developing human fetal brain. Injection of LCMV into the neonatal rat brain results in a selective infection of the cerebellar cortex and dentate gyrus. This infection triggers an acute distruction of the cerebellum and a delayed mortality of dentate granule cells. The objective of this proposal is to identify the mechanisms underlying the acute and the delayed pathologic changes. The first aim is to determine the dynamics of the viral infection and the time course and magnitude of the granule cell loss. Viral localization will be determined by immunocytochemistry and insitu hybridization and regional viral load will be determined by titer and Rnase protection assay. Stereological methods will be used to define the time course of the neuronal loss. The second aim is to test the hypothesis that the pathologic changes are immune mediated and to identify the immune cell types and molecules involved. LCMV infection will be studied in immune deficient rats. The role of specific immune cell types will be determine by immunocytochemistry and FACS analysis. The role of cytokines and of nitric oxide over- production in both the acute and delayed pathologic changes induced by LCMV will be explored. The third aim is to explore the possibility that alpha-dystroglycan (a-DG) is the cellular receptor for LCMV in the neonatal rat brain and plays a critical role in the tropism of the infection in vivo. The topography of a-DG expression in the developing brain will be demonstrated by immunohistochemistry and compared with the spatial distribution of LCMV infection. Double labeling experiments will determine whether LCMV infected brain cells universally express a-DG. The importance of a-DG in influencing the tropism and infectivity of LCMV will be examined by blocking a-DG with an antibody prior to exposure of brain slices to LCMV.